1. Field of the Invention
This invention relates to planar heating apparatus that is conformable to nonplanar shapes such as cylindric surfaces of pipes and tanks and the like.
2. Description of the Prior Art
In many industrial installations it is necessary to apply heat to the wall of a tank or pipe at one or more localized areas. A convenient technique for applying heat is the provision of an electrically powered unit containing one or more resistive heating elements and being conformable to the surface of the tank or pipe. One such unit is exemplified by U.S. Pat. No. 3,904,850 in which there is disclosed a multilayer flexible heater panel the mechanical integrity of which is maintained by an insulative face layer having side portions folded over the edges of the device. The patented panel also includes a flexible ground layer formed of wire screen embedded between layers of insulation.